Well okay; the humans aren't pets, they're emotional support animals. Not a huge improvement though.
I dunno; it doesn't bother me at all.
What bothers me is pretending that the Culture is humanity's. Or that humans are in any way relevant to the whole plotline. It's like if somebody rewrote all the great works of literature from the perspectives of the protagonists' dogs, and then threw away the originals, and pretended that this was somehow a useful perspective. That would bother me.
I think family is a better metaphor. Families do provide emotional support as well.
The Minds have no reason to treat humans well. Humans have a powerful evolutionary motivation to treat their kin well.